Jiro Azuma is a strong fighter who has his dark mode at the ready but Naruto is the guy who really mastered how to fight while using another being’s power. Naruto has ascended to heights far beyond that of what Jiro has made it to. Unfortunately for Jiro his story ended rather early so he just couldn’t make it to the next level. Naruto has experience on his side as well as a whole combo worth of super forms. Naruto wins.
Jiro is an incredible hand to hand fighter and in his fused state he has a lot of ranged options as well. Fighting monsters is what he does and so not even a creature like Raikou is going to get the better of him here. Raikou’s got a lot of thunder attacks but simply isn’t fast enough to keep up with Jiro or durable enough to take the hits. Jiro Azuma wins.